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Use of methylhydroxyethyl cellulose as cement additive

a technology of methylhydroxyethyl cellulose and cement additive, which is applied in the direction of clayware, sealing/packing, and well accessories, etc., can solve the problems of weakening the structure, affecting the quality of cement, so as to reduce the potential incompatibility and simplify the operation in the field

Active Publication Date: 2012-10-25
BJ SERVICES LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0011]Methylethylhydroxy cellulose (MHEC) may be used in the cementing of wells, including oil, gas, water, injection, disposal, storage and geothermal wells. The use of MHEC in cement slurries prevents and / or reduces the occurrence of gas channeling. In addition, MHEC controls fluid loss, minimizes free fluid, improves slurry stability, and stabilizes foam.
[0015]In another embodiment, MHEC is used in cement slurries to retard the effect on thickening times in the slurry.
[0018]The use of MHEC in cement slurries provides an economical design of cement systems reduces potential incompatibilities between combinations of additives in the cement slurry and simplifies operations in the field.

Problems solved by technology

Gas channeling in a cement composition is a common problem in the oil and gas industry.
It is in this transition stage that the cement composition is susceptible to formation gas entering into the cement sheath.
Channeling in a cement composition weakens the structure.
Another common problem in well cementing is the loss of liquid fluid from the cementitious slurry into porous low pressure zones in the formation surrounding the well annulus.
Fluid (liquid and / or gas) loss is undesirable since it can result in dehydration of the cementitious slurry.
In addition, it may cause the formation of thick filter cakes of cement solids.
In addition, fluid loss can damage sensitive formations.
Controlling gas in light weight cements, especially at low temperatures, has also been an industry problem for a number of years because the additive systems that are generally used or employed are better suited for heavier or higher density cements.
This quantity increases to a point that is cost prohibitive for lower density cement compositions.

Method used

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  • Use of methylhydroxyethyl cellulose as cement additive

Examples

Experimental program
Comparison scheme
Effect test

examples 1-13

[0043]Cementitious slurries of desired density were prepared by mixing neat Joppa Class H Portland cement, optionally mixed with fly ash, with fresh tap water at room temperature. To the slurry was added methylhydroxyethyl cellulose (MHEC) and, optionally, sodium lignosulfonate (“SLS”) as set retarder. (Comparative slurries were also prepared using, in place of MHEC, HEC from one of three suppliers.) The resultant slurry was kept agitated by occasional stirring. The free fluid content of the slurries was determined in accordance with procedures in API Recommended Practice 10B-2, First Edition, July 2005. The amount of fluid loss was determined at a designated temperature in accordance with procedures in API Recommended Practice 10B, Twenty-Second Edition, December 1997, incorporated herein by reference. Standard API viscosity reading readings were taken on a Fann 35 viscometer, at 120° F., 160° F. or 170° C. The results are tabulated in Table I:

TABLE IFluidFreelossExampleDensityAddi...

examples 14-16

[0044]Cementitious slurries of 15.6 ppg density were prepared by mixing at room temperature 50 / 50 (v / v) fly ash / Joppa Cement H cement mix with fresh tap water. To the slurry was added 0.2% BWOC polynaphthalene sulfonate dispersant admixture (commercially available as CD-32 from Baker Hughes Incorporated) and 0.2 gallons per sac (gps) of an ammonium salt of ethoxylated alcohol sulfate foaming agent, commercially available as FAW-20 from Baker Hughes Incorporated. Further, to one slurry was added 0.2% BWOC MHEC and to another slurry was added 0.2% BWOC HEC. The stability of the foam was determined starting at a 15.6 ppg density and foamed down to 11.6 ppg. The results are shown in Table II. Further, the density of the cured cement was determined in a BP settling tube at 120° F. and the results shown in Table III, below. The tests were conducted in accordance with the protocol set forth in API Recommended Practice 10B-2 and ISO 10426-2.

TABLE IIFoamHomogenousstabilityStabledensitytestAd...

examples 16-17

[0045]Cementitious slurries having a density of 15.0 ppg were prepared by mixing neat Joppa Class H Portland cement and fly ash (50:50 v / v) with fresh tap water at room temperature. To one slurry was added methylhydroxyethyl cellulose (MHEC) and to the second slurry was added hydroxyethyl cellulose (HEC). Sodium lignosulfonate (“SLS”) as set retarder was further added to one of the slurries in accordance with Table IV below:

TABLE IVMHEC,HEC,SLS,Amt Water,Ex. No.[BWOC][BWOC][BWOC]gps160.4—0.14.487Comp. Ex. 17—0.8—4.536

The gas volume and pore pressure of the cementitious slurries were determined over an extended period of time. These were determined by a Gasflow Model which was used to simulate the well configuration where the cemented annulus is between pressurized gas sand and a low pressure permeable zone. (In a typical well configuration where the cementitious slurry in the annulus between the casing and the formation, the cement is exposed to a highly permeable gas zone and a low...

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Abstract

Methylhydroxyethyl cellulose may be used as an additive in cement slurries in the treatment of wells to prevent or reduce the occurrence of gas channeling. In addition to acting as a gas control additive, methylhydroxyethyl cellulose controls fluid loss, minimizes free fluid and stabilizes foam during cementing of the well.

Description

FIELD OF THE INVENTION[0001]This invention relates to the use of methylhydroxyethyl cellulose (MHEC) as an additive for cement compositions. The MHEC may be used as a multipurpose additive for use to prevent and / or control gas channeling, control fluid loss, minimize free fluid, improve slurry stability and / or stabilize foam.BACKGROUND OF THE INVENTION[0002]During construction of a well penetrating a subterranean formation, a rotary drill is typically used to bore through the subterranean formation to form a wellbore. Once the wellbore has been drilled, a pipe or casing is lowered into the wellbore. A cementitious slurry and a displacing fluid, such as a drilling mud or water, is pumped down the inside of the pipe or casing and back up the outside of the pipe or casing through the annular space between the exterior of the pipe or casing and the wellbore. The cementitious slurry is then allowed to set and harden.[0003]A primary function of the cementing process is to restrict fluid m...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): E21B33/14C04B16/02
CPCC04B24/383C04B28/04C09K8/487C09K8/493C04B2103/46C04B24/38C04B33/138C09K8/467
Inventor BRAY, WINDAL SCOTTBRANDL, ANDREAS
Owner BJ SERVICES LLC
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